The present invention relates to an electric compressor.
An electric compressor includes a compressing portion for compressing and discharging refrigerant, an electric motor for driving the compressing portion, and a housing for accommodating the compressing portion and the electric motor. An inverter cover, which accommodates an inverter for driving the electric motor, is fixed to the housing. If made of metal, the inverter cover increases the weight of the electric compressor. Thus, to minimize the increase in the weight of the electric compressor, the weight of the inverter cover may be reduced, for example, by making the inverter cover with plastic. For example, refer to Japanese Laid-Open Patent Publication No. 2004-162618 (a first prior art) and Japanese Laid-Open Patent Publication No. 2002-155862 (a second prior art).
The electric compressor of the first prior art has an inverter case (inverter cover). The inverter case includes a base portion, which is formed integrally with the motor housing on the outer circumferential surface of the motor housing, a frame portion placed on a base surface of the base portion, and a lid portion for closing the upper opening of the frame portion. A part of the inverter case, or a frame portion, is formed of plastic.
The inverter case of the second prior art has a main body, which is made of plastic. Metal plating is applied to the inside of the inverter case, for example, through insert molding.
However, in the inverter case of the first prior art, external electromagnetic noise can intrude from the frame portion and flow into the inverter. Also, in the inverter case of the second prior art, the metal plating cannot ensure the strength of the inverter case. Further, due to changes in the temperature in the engine compartment, where the compressor is placed, the difference in the rate of the thermal expansion between the metal and the plastic can cause the metal plating to peel off the inverter case. In such a case, the metal plating can no longer shield against external electromagnetic noise. Also, a peeled flake of the metal plating can contact the inverter, causing short circuiting.